Thread: need to stepdown 12v to 2.5/3v for wireless controller

Originally Posted by mikevsgeek

I am using a wireless xbox control to transmit my steering wheel controls to my jeepPC seeing as how my clockspring doesn't have the wires needed.

the wireless controller I am using uses 2 AAA batteries should be providing about 3v worth of juice, but its working on 2.3v right now so 2.5-3v would be perfect..

the horn has a 12v line which I can tap into, but i am having a tough time finding a stepdown powersupply... actually I would like to just assembly one myself.. needs to be relatively small/flat, like maybe the size of business card or so...

can anyone help me out with an electical design or maybe point me to in the right direction to existing schematics?

How many amps?

There are several Voltage Regulators that you can use to accomplish what you need. It isn't hard at all, and will be very small.

I like the LM338K. It is not cutting edge stuff, but it will work. This is an adjustable voltage regulator, so you can set it where you want/need it, and is capable of supplying 3 amps of power when adequately cooled. If you require much less amperage, then you should have no heat issue with it.

Michael

No, I wouldn't think it needs anyewhere near 3 amps, but I hate speculating about specs of devices. I only wanted to know so that the device can supply sufficient amperage. The resisters with a 338 only set the voltage, not the amperage.

The more "robust" the regulator, the less worry about heat and drawing too many amps.

Michael

Like I said, there are many ways to accomplish this.

I would just add that in the OP situation, any type of "switching" is a bad idea. Switching devices oscilate, causing an RF field that can effect wireless communications. It can rduce the effective range of a wireless device significantly. While this can be overcome, it will take some work and additional parts which are not needed with an LM338.

Just keep that in mind.

Michael

yeah, a regulator like wired mentioned, or even a fixed 3v regulator would get the job done... I'd imagine the load is going to be a few hundred miliamps, & even then not continuous, a regulator with a small cap on the input & output would do fine...

also, if your using an atx power supply for your pc, you already have a 3.3v feed that can be used from that with no add'l components..

Don't make thing complicated.
Get one of those cigarette adapter that has selectable voltage. Normally those are good for about 850mA and cost about 15 bucks or less.